Dosage of chemotherapeutic drugs is a tradeoff between efficacy and side-effects.Liposomes are nanocarriers that increase therapy efficacy and minimize side-effects by delivering otherwise difficult to administer ther...Dosage of chemotherapeutic drugs is a tradeoff between efficacy and side-effects.Liposomes are nanocarriers that increase therapy efficacy and minimize side-effects by delivering otherwise difficult to administer therapeutics with improved efficiency and selectivity.Still,variabilities in liposome preparation require assessing drug encapsulation efficiency at the single liposome level,an information that,for non-fluorescent therapeutic cargos,is inaccessible due to the minute drug load per liposome.Photothermal induced resonance (PTIR) provides nanoscale compositional specificity,up to now,by leveraging an atomic force microscope (AFM) tip contacting the sample to transduce the sample's photothermal expansion.However,on soft samples (e.g.,liposomes) PTIR effectiveness is reduced due to the likelihood of tip-induced sample damage and inefficient AFM transduction.Here,individual liposomes loaded with the chemotherapeutic drug cytarabine are deposited intact from suspension via nano-electrospray gas-phase electrophoretic mobility molecular analysis (nES-GEMMA) collection and characterized at the nanoscale with the chemically-sensitive PTIR method.A new tapping-mode PTIR imaging paradigm based on heterodyne detection is shown to be better adapted to measure soft samples,yielding cytarabine distribution in individual liposomes and enabling classification of empty and drug-loaded liposomes.The measurements highlight PTIR capability to detect ~ 103 cytarabine molecules (~ 1.7 zmol) label-free and non-destructively.展开更多
Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as"unperturbed", we found that ne...Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as"unperturbed", we found that neither could accurately measure the size of NPs featuring a broad size distribution, e.g., aggregates. Because many real-world NP samples consist of aggregates, this finding was of considerable concern. The data showed that the protocols introduced errors into the measurement by either inducing agglomeration artefacts or providing a skewed size distribution towards small particles (skewing artefact). The focus of this work was to develop and apply a mathematical refinement to correct the skewing artefact. This refinement provided a much improved agreement between EM and a reference methodology, when applied to the measurement of synthetic amorphous silica NPs. Further investigation, highlighted the influence of NP chemistry on the refinement. This study emphasised the urgent need for greater and more detailed consideration regarding the sample preparation of NP aggregates to routinely achieve accurate measurements by EM. This study also provided a novel refinement solution applicable to the size characterisation of silica and c让rate-coated gold NPs featuring broad size distributions. With further research, this approach could be extended to other NP types.展开更多
文摘Dosage of chemotherapeutic drugs is a tradeoff between efficacy and side-effects.Liposomes are nanocarriers that increase therapy efficacy and minimize side-effects by delivering otherwise difficult to administer therapeutics with improved efficiency and selectivity.Still,variabilities in liposome preparation require assessing drug encapsulation efficiency at the single liposome level,an information that,for non-fluorescent therapeutic cargos,is inaccessible due to the minute drug load per liposome.Photothermal induced resonance (PTIR) provides nanoscale compositional specificity,up to now,by leveraging an atomic force microscope (AFM) tip contacting the sample to transduce the sample's photothermal expansion.However,on soft samples (e.g.,liposomes) PTIR effectiveness is reduced due to the likelihood of tip-induced sample damage and inefficient AFM transduction.Here,individual liposomes loaded with the chemotherapeutic drug cytarabine are deposited intact from suspension via nano-electrospray gas-phase electrophoretic mobility molecular analysis (nES-GEMMA) collection and characterized at the nanoscale with the chemically-sensitive PTIR method.A new tapping-mode PTIR imaging paradigm based on heterodyne detection is shown to be better adapted to measure soft samples,yielding cytarabine distribution in individual liposomes and enabling classification of empty and drug-loaded liposomes.The measurements highlight PTIR capability to detect ~ 103 cytarabine molecules (~ 1.7 zmol) label-free and non-destructively.
文摘Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as"unperturbed", we found that neither could accurately measure the size of NPs featuring a broad size distribution, e.g., aggregates. Because many real-world NP samples consist of aggregates, this finding was of considerable concern. The data showed that the protocols introduced errors into the measurement by either inducing agglomeration artefacts or providing a skewed size distribution towards small particles (skewing artefact). The focus of this work was to develop and apply a mathematical refinement to correct the skewing artefact. This refinement provided a much improved agreement between EM and a reference methodology, when applied to the measurement of synthetic amorphous silica NPs. Further investigation, highlighted the influence of NP chemistry on the refinement. This study emphasised the urgent need for greater and more detailed consideration regarding the sample preparation of NP aggregates to routinely achieve accurate measurements by EM. This study also provided a novel refinement solution applicable to the size characterisation of silica and c让rate-coated gold NPs featuring broad size distributions. With further research, this approach could be extended to other NP types.
